Screw propeller



July 7, 1936. v s 2,046,538

I scREw PROPELLER Filed Au'g.. 31, 1933 -P Vargas WW awz W Patented July7, 1936 UNITED STATES PATENT OFFICE Application August 31, 1933, SerialNo. 687,705 In Italy April 6, 1933 4 Claims.

The present invention has for its object a special modification to thetrack of the screw-propellers, whatever may be the fluid wherein theyoperate, with a view to attaining a greater per- 5 fection in theperformance and thence a better emciency. 4

To this effect, each blade of the propeller at its base, i. e. at thezone adjacent the hub, instead of being in a sole piece, is subdivided,in radial direction, into two distinct portions or elements,

which are separate from each other, so as to constitute an opening orhollow, for the passage of the fluid through the body of the blade, fromthe front side to the rear one of the latter, with the special featuresthat:

1. The borders or adjacent peripheries of the said parts or elementswhereinto the blade is divided at its base, result superposed to eachother for a limited width and for the whole height of 20 the opening,when the blade itself is observed in projection over a plane at rightangles to the axis of rotation of the screw hub; consequently, on thesame projection of the blade no hole, or aperture or hollow whatever isperceived for the 25 passage of the fluid from the front to the .rearside, but on the contrary, and in correspondence to the subdivision ofthe blade, the sole line of contour or projection of the edge of one ofthe two elements into which the base of the blade 30 is subdivided andwhich superposes itself to the other;

2. Vice-versa, if the blade itself is observed as lying on a differentplane from that which is at right angles to the axis of rotation of thehub and 35 which is mentioned under 1), through the body of the blade apassage or aperture is observed which has a certain width at the basenear the hub and which gradually decreases towards the top up to end inthe form of an acute angle with- 40 in the body of the blade itself,such height being correspondent to the contour or projection line of theborder of one of the two elements of the blade, and which is observed inthe projection of the blade over the plane at right angles to the 45axis of rotation of the hub beforementioned.

2. Such aperture for the passage of the fluid through the body of theblade, characterized as aforesaid, in addition to whatever dimensions,in relation to the direction of the rotatory motion 50 of the blade, hasalways the direction from the corner of entry of the blade to that ofegress, and may have either a rectilinear or a curvilineal direction.

Independently of the previous characteristics,

55 which form the object of the present invention and which are appliedon the single blades of a screw-propeller, the blades themselves mayhave a nature and form whatever either in respect to the generatrix ofthe helicoidal surface or in re; spect to the constant or variablepitch. 5

In the accompanying drawing there is illustrated, only by Way ofexample, some views of the blades conceived in accordance with thepresent invention. Fig. 1 is a view in axial direction, i. e. it showsthe blade of the screw projected on a plane which is at right angles tothe axis of rotation of the propeller hub; Fig. 2 shows in plan view thecorresponding section of the blade, at the point of its connection tothe hub according to the present invention, observed in the samedirection as that of the rotation axis of the hub; Fig. 3 shows theblade upset on the plane at right angles to the axis of rotation of thehub, with the detail of the various sections in the body of the bladeitself; Fig. 4 is the cross view of the blades on a plane different fromthat at right angle to the axis of rotation of the propeller hub.

Referring particularly to Fig. 1, I denotes the hub of the screwpropeller and 2 the axis of rotation of same; 3 and 4 are the twoelements, or parts, into which the blade is subdivided at the bottom inthe zone adjacent to the hub, and 56 is the contour or superpositionline of the two bottom elements of the blade, of which the element 3lies before the other 4. 80

The lines 189-l0--|l and I2 indicate the various sections effected inthe bodyof the blade, in (it: three projections represented in Figs. 1-3an With reference to Fig. 2, the line 'l-'| indicates the plan view ofthe section I, shown in Fig. 1, observed in the direction of the axis ofrotation of the hub 2 and in which are shown in section (instead of theunique section of the blade indicated in dash line l3l3 as in the.ordinary cases) 40 the two elements or parts into which the blade issubdivided at the bottom, in the zone of connection to the hub. In thissection it is clearly shown how the two elements superpose on each otherwith the adjacent sides, in the direction of the rotation axis of thehub 2, i. e. when they are observed on the plane at right angles to thesaid axis of rotation; whereas, when they are observed in the directionl4, 1. e. on a plane different from the one just mentioned, they showall the aperture for the passage of the fluid l5.

With reference to Fig. 3, this shows the lower zone of the blade,adjacent to the hub, with the sections 1 and 8 of the two bottomelements whereinto the blade is subdivided at that point, as 66 inradial direction drawn in the body of the'blade itself from the planeil--I8 indicated in Fig. 3.

Such section is indicated by 5-!6, and 5-43 denotes the aperture of holefor the passage of the fluid through the body of the blade, aperturethat is obtained thanks to the special subdivision of the blade itself,circumscribed to the base, near the hub.

Though for descriptive reasons the present invention has been based onthe foregoing specification and on the accompanying drawing, yet manypractical modifications may be made in the realization of the invention.Thus, for instance, it will be possible to modify the shape and width ofthe passage apertures through the'two base elements into which the bladeis subdivided, the conformation of the body of these two base elements,etc. such modifications and [others being however included within thescope of the invention as set forth in the following claims.

Having now particularly described and ascertained the nature of thepresent invention and in what manner the same is to be performed, Ideclare that what I claim is:

1. A screw blade constituted, in the radial direction, by two differentzones of helicoidal surfaces;

the first zone which, for about half of the radial length of the bladeextends inwardly from the tip thereof and being of the usual screwshape, and. the second zone, which adjoins the first zone and which iscontinued to the boss, into two separate elements; the said elements,and the cross sections of such elements in planes perpendicular to thediametral plane and included between the boss and the limit of the firstzone, being arranged one on each side-cf said diametral plane, one ofthe said sections being displaced forwardly of the other to the entranceedge of the helicoidal sur-, face of the first of said elements and theexit edge of the helicoidal surface of the second element being locatedupon the said diametral plane on opposite sides thereof so that, if theentire blade is viewed in elevation in the direction of the axis ofrotation of the boss, no aperture is visible in the front face of theblade.

2. A screw blade constituted, in the radial direction, by two differentzones of helicoidal surfaces;

the first zone which, for about half of the radial length of the bladeextends inwardly from the tip thereof and being of the usual screwshape, and the second zone, which adjoins thefirst zone and which iscontinued to the boss, into two separate elements; the said elements,and the cross sections of such elements in planes perpendicular to thediametral plane and included between the boss and the limit of the firstzone, being arranged one on each side of said diametral plane, one ofthe said sections being displaced forwardly of the other, the entranceedge of the helicoidal surface of the first of said elements and theexit edge of the helicoidal surface of the second element being locatedupon the said diametral plane on opposite sides thereof so that, if theentire blade is viewed in elevation in the direction of the axis ofrotation of the boss, no aperture is visible in the front face of theblade, the generatrices of the helicoidal surfaces of the two elementsinto which the blade is subdivided adjacent to the root being parallelto one another, but approaching one another gradually so as to form asingle generatrix, thus generating two helicoidal partial surfaces eachof which merges into the single continuous helicoidal surface of thefirst zone of the blade.

3. A screw blade constituted, in the radial direction, by two differentzones of helicoidal surfaces;

the first zone which, for about half of the radial length of the bladeextends inwardly from the tip being arranged one on each side of saiddiametral plane, one of the said sections being displaced forwardly ofthe other, the entrance edge of the helicoidal surface of the first ofsaid elements and the exit edge of the helicoidal surface of the secondelement being located upon the said diametral plane on opposite sidesthereof so that, if the entire blade is viewed in elevation in thedirection of the axis of rotation of the boss, no aperture is visible inthe front face of the blade, all the sections transverse andperpendicular to the diametral plane of division-of the blade, at thezone adjacent to the boss, the rear contours of the elements being linesparallel to one another.

4. A screw blade constituted, in the radial direction, by two differentzones of helicoidal surfaces;

the first zone which, for about half of the radial length of the bladeextends inwardly from the tip thereof and being of the usual screwshape, and the second zone, which adjoins the first zone and which iscontinued to the boss, into two separate elements; the saidelements, andthe cross sections of such elements in planes perpendicular to the saidplane and included between the boss and the limit of the flrstzone,being arranged one on each side of said diametral plane, one of the saidsections being displaced forwardly of the other, the entrance edge ofthe helicoidal surface of the first of said elements and the exit edgeof the helicoidal surface of the second element being MANF'REDI PALULEBOVARGAS.

